Final answer:
To grant extra access to a single Salesforce user, an administrator should use Permission Sets. This allows the assignment of additional privileges for specific reports or objects without changing the user's profile.
Step-by-step explanation:
To grant a single user additional access to an object in Salesforce, one should use the feature known as Permission Sets. Permission Sets allow administrators to grant extra permissions to users on top of what they have through their profile without changing the profile. It is a flexible and scalable way to assign extra privileges without the need to create extra profiles.
For instance, if a user needs access to a specific report or object that is not included in their profile, the admin can create a permission set that gives access to that report or object and then assign it to the specific user. This approach maintains the organization and security of the system by not overloading profiles with additional permissions.